The present invention relates to a miniature pointing device for use with portable electronic apparatus, such as notebook computers, hand-held electronic games, so-called "personal digital assistants" (PDAs), and the like. More particularly, the present invention relates to a miniature track ball pointing device with a built-in selector for pointing to and selecting an object displayed on a display screen.
It is now commonplace for a personal computer to include a pointing device for selecting objects and manipulating data. Generally, the pointing device moves a pointer around a display screen, and one or more buttons are activated to select an object being pointed to or to move a cursor to the location of the pointer. A number of different pointing devices have been developed to date, including touch pads, magnetic tablets, trackballs, and mice.
A touch pad is a pressure-sensitive pointing device having a two-dimensional array of pressure sensors, with each sensor corresponding to a coordinate position on a display screen. A finger is dragged across the array of sensors, and the direction of movement of the finger moves a pointer on the display screen in that direction. A button selector is pressed to select an object being pointed to by the pointer or to move a cursor displayed on the display screen to the location of the pointer. Optionally, a pressure-sensitive selector located below the two-dimensional array of pressure sensors may be used, wherein the pressure-sensitive selector is activated when it is tapped at a pressure above a predetermined value greater than the pressure sensed by the two-dimensional array of pressure sensors.
A problem with the use of touch pads is that users may not have a sufficiently delicate finger control which is required to move the pointer without overshooting the desired pointer position. User frustration can result from repeated attempts to position a pointer caused by clumsy fingers. Similarly, a problem with the use of a pressure-sensitive selector is that tapping with inadequate pressure will fail to activate the selector but instead will likely lead to inadvertent movement of the pointer, thus causing user frustration at having to re-position the pointer.
A magnetic tablet is similar to a touch pad but uses magnetic sensors instead of pressure-sensitive sensors. A pen having a magnetic tip is dragged across the tablet, and the direction of movement of the pen moves a pointer in that direction. A button selector is pressed to select an object being pointed to by the pointer or to move a cursor to the location of the pointer.
A problem with the use of magnetic tablets is that they require the use of a magnetic pen which can be sensed by the magnetic sensors. Thus, a user must move his fingers away from a keyboard area in order to manually grasp and move the pen to activate the magnetic sensors, which is a slow and often annoying way to point at an object on a display screen because of all the hand movement involved.
A mouse is the most common of the known pointing devices and converts electrical data derived from movement of the mouse on a surface to vector movements of a pointer displayed on a display screen. A mouse generally includes a ball-shaped roller protruding from its lower surface such that when a user grasps the mouse and drags it along a table top the roller rolls and engages x and y movement sensors. The sensors, in turn, convert the roller's movement into electrical signals for moving the pointer on the display screen. A button is incorporated on an upper surface of the mouse for use as a selector.
A problem with the use of mice is that they require a table top or the like for dragging the roller to move the pointer. Thus, mice generally are not well suited for use with compact portable electronic apparatus where table tops are not always available. Additionally, a user must move his hand away from a keyboard area, for example, in order to use a mouse, thus requiring the user go through several hand and arm motions.
A trackball is similar to a mouse but has a ball-shaped roller protruding from its top surface. A user rolls the roller with his finger in order to move a pointer on a display screen. A button positioned near the ball is used as a selector.
A disadvantage to using trackballs for compact portable electronic apparatus is that both a roller and a separate selector button must be accommodated on the apparatus, thus enlarging the size of the apparatus.